The 64S can accept AVB inputs from the 32R and/or NSBs simultaneously.
The 32r can accept AVB inputs from the 64S and NSBs simultaneously.
The only limitation is that the 32R cannot mix 64 channels. It can receive up to 64 channels via AVB and then digitally patch those to whatever channels you want. The 32R will only ever show 32 normal input channel faders though. This goes for all of the other Series III mixers (blue or gray) as well. The 64S is the only mixer capable of mixing 64 channels.
AVB is very flexible so you can have almost any mixture of consoles, rack mixers, NSBs, and EarMixes as long as you pay attention to how your clocking is setup. Only one mixer should have the clock set to "Internal". Any device that the main mixer is receiving audio from also needs to have an AVB Send from the main mixer connected to it so that device can receive clock sync.
